dccp: Add missing annotation for dccp_child_process()

Sparse reports a warning at dccp_child_process()
warning: context imbalance in dccp_child_process() - unexpected unlock
The root cause is the missing annotation at dccp_child_process()
Add the missing __releases(child) annotation

Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/minisocks.c

@@ -216,6 +216,7 @@ EXPORT_SYMBOL_GPL(dccp_check_req);
  */
 int dccp_child_process(struct sock *parent, struct sock *child,
 		       struct sk_buff *skb)
+	__releases(child)
 {
 	int ret = 0;
 	const int state = child->sk_state;